1. Field of the Invention
The present invention relates to multipane insulating glass for appliances with an inner-chamber temperature which is lower than ambient temperature, in particular for viewing doors of refrigerators and freezers. The glass comprises at least two panes which are of approximately equal size and are arranged at a distance from one another, the distance being maintained by a spacer which runs continuously around the vicinity of the edge. One of the two outer panes is provided with an electrically conductive, transparent coating on its side which faces towards the space between the panes. The present invention furthermore relates to a process for producing coated flat glass materials for such insulating glass materials.
2. Background Information
In particular, upright and chest refrigerators and freezers have viewing doors with multipane insulating glass materials of the type described in the introduction. These materials delimit the cold area in the inner chamber from the higher ambient temperature.
In refrigerators, and in particular in freezers, the temperature difference between the inner chamber and the environment often results in the formation of condensation. The condensation from the atmospheric humidity which is precipitated on the pane makes it difficult or impossible to see the cooled articles in the inner chamber. In order to substantially prevent this, or in order for the precipitated condensation to be removed again quickly, in the appliances which are commercially available, the pane of the multipane insulating glass which faces towards the outside area is heated. This is achieved by means of a treatable, electrically conductive, transparent coating on the inside of the pane, i.e. on its side which faces towards the space between the panes. Such a coating consists, for example, of doped SnO.sub.2 which is applied, for example, using a hot-spray process and is then fired.
To this end, before the coating operation, the pane of glass is cut to the desired size and a mask which covers the peripheral area is applied to the pane, so that the coating is kept off the subsequent contact surface for the spacer. This is necessary, despite the standard adhesive bonding using adhesives which are non-conductive in the cured state, in order to prevent the metal spacers used from causing spark-overs onto the spacers when the pane is heated, so that voltage is passing through the spacers, which may lead to overheating.